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  1. AnalogKid

    5V boost converter efficiency?

    96% efficiency is a fantasy, achievable only in one specific set of conditions (input voltage, output voltage, output current). And that spec might be the calculated peak efficiency of the switching regulator chip by itself, not including other circuit losses. Boost converters are the least...
  2. AnalogKid

    Is this circuit possible?

    So does the circuit in post #1. Unless he has the only low-cost toggle switch on the planet that is make-before-break, the inherent air gap between the two circuits is more than adequate for 12 V isolation, is less complicated to wire, doesn't dissipate any heat as diodes would, etc...
  3. AnalogKid

    How to delay the relay

    Replace the DPDT switch with a DPDT center-off switch. This has a third detent position in the middle where no contacts are closed. You can count the three seconds in your head. To do this electronically requires a timer circuit driving two relays, so there can be a condition where neither is...
  4. AnalogKid

    Reducing amps in a circuit without change in the voltage

    Pulse Width Modulation. Most small switchers have a constant-frequency square wave oscillator of 50 kHz - 200 kHz. The duty cycle or pulse width of the waveform varies depending on the load current. Low cost circuits have a limited range of pulse width...
  5. AnalogKid

    RS232 message to pulse

    Is the RS-232 message at true 232 signaling levels (+/-9 V or so), or at logic levels (5 V or 3.3 V)? A true monostable circuit (with feedback) will put out a constant pulse for each message. That can increment a CD4017 counter that steps through its outputs like a rotary switch until it gets...
  6. AnalogKid

    Reducing amps in a circuit without change in the voltage

    Most switching power supplies, especially fully isolated ones, have a minimum load requirement. This comes from a combination of the magnetics requiring a minimum energy flow to operate correctly, and/or a regulator circuit not able to manipulate near-zero currents correctly due to PWM limits...
  7. AnalogKid

    Explain this circuit: Digital linear PSU

    Max output current can be calculated from Figure 6. Input voltage range is in section 6.3. Note that the power for all of the stated parameters is +/-15 V. Performance at other voltages is in some of the plots. The input common mode voltage range is not +/-4 V. It is Vcc-4V to Vee+4V. So if...
  8. AnalogKid

    Explain this circuit: Digital linear PSU

    The source for the non-inverting input, the output of the reference circuit, has no DC load to ground to stabilize the output of its emitter follower T2. Wherever the input to the negative feedback voltage divider attaches to the circuit, that is the "output" as far as the composite amplifier...
  9. AnalogKid

    Voltage regulator for LED panel

    LED brightness changes with the total energy through the diode. Voltage-mode, current-mode, PWM, whatever, for a particular brightness you need a certain amount of energy from the source. The energy at 50% brightness will be less than at peak brightness, but the conversion circuit efficiency...
  10. AnalogKid

    mesh

    May 5, 2016 The early part of the century a time of rampant technological change, with new ideas, inventions, and refinements bursting upon the world at a dizzying pace, straining the social and economic fabrics of the time. I’m speaking, of course, of the 1900’s and the automobile. In 1910...
  11. AnalogKid

    Explain this circuit: Digital linear PSU

    It is. In the world of analog circuits, "multiply" can mean an analog multiplier, which is a very different circuit from an opamp gain stage. But the basic opamp gain stage you are familiar with *does* multiply the input by a constant. So in non-electrical-engineering English you are correct...
  12. AnalogKid

    Explain this circuit: Digital linear PSU

    There are two fundamentally different ways of designing a variable-output voltage power supply, and you are confusing the two. The first schematic is a fixed-gain DC amplifier driven by a variable input voltage. The gain equation is stated correctly right below the schematic. If you drive...
  13. AnalogKid

    RC charging and discharging

    No, it isn't. The two resistors form a Thevenin equivalent voltage source that is the maximum voltage across the capacitor, with a Thevenin equivalent output impedance that sets the R-C time constant. https://en.wikipedia.org/wiki/Th%C3%A9venin's_theorem ak
  14. AnalogKid

    Temperature

    Separate from temperature measurement IC's are thermostat IC's. These have a switching output rather than an analog voltage. https://para.maximintegrated.com/en/search.mvp?fam=temp_sw&hs=1 ak
  15. AnalogKid

    Voltage regulator for LED panel

    Sure it is. Once you commit to building something with a pre-fab switching power supply inside, the only issue is which power supply. If you use an adjustable boost converter to drive 10 parallel strings of 10 LEDs in series, the resistor power loss is greatly reduced. Plus, you are reducing...
  16. AnalogKid

    Oring of two Clocks

    Disagree. Yours has a DC input impedance of 100 ohms, and the transient impedance is even lower. 100 ohms is hard to drive on purpose, let alone by accident. Plus, the higher the source output impedance, the better the noise immunity. OTOH, the HC123 has a CMOS buffer between the input pin...
  17. AnalogKid

    Oring of two Clocks

    If the two input frequencies are stable, the monostable circuit can be tuned to change over almost instantly when the 225 signal appears, and in 1.1 cycles when it disappears. No way a 567 can acquire or release that quickly. ak
  18. AnalogKid

    Output Voltage Selector

    Yes, there is. The two FETs are connected such that their internal parasitic diodes are back-to-back. This prevents reverse current flow when the FETs are off. Because it uses two identical transistors and only one drive signal, it is considerably easier than implementing a full or half...
  19. AnalogKid

    How is this Possible

    S CC HHH EEEE MMMMM AAAAAA TTTTTTT IIIIIIII CCCCCCCCC ak
  20. AnalogKid

    Call Progress tone

    Written by an ancient from the previous century - !!! ak
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